SOME ADAPTATIONS & IMPERFECTIONS
CHECK THE CATEGORY COLUMN APPROPRIATE FOR EACH FEATURE

AD=adaptation

CO=contrivance

VE=vestigial feature

AT=atavism

FEATURES

AD

CO

VE

AT

1. Our spinal
column

2. Our larynx,
its lower position

3. Our eustachian
tube

4. Human tails

5. "Wisdom
Teeth"

6. Our ear-wagging
muscles

7. Sickle-cell
Anemia

8. Flippers
of seals and sea lions

9. Tree kangaroos:
legs and feet

10. Anteaters'
teeth in embryos only

11. Salamanders:
gills and fins on embryos only

12. Hollow
bones in flying birds

13. Hollow
bones in flightless birds

14. Cave dwelling
animals: sightless eyes

15. Male Booby
birds: nesting material - for courting only

16. Some beetles:
useless wings beneath wing covers

17. Some whales,
sometimes with pelvis, thigh bones

18. Teeth in
some baleen whales (embryos only)

19. Pythons,
boa constrictors: with pelvis & tiny limbs

20. Panda's
"thumb" (6th digit from wrist bone)

21. Extra Horse Toes

SOME ADAPTATIONS & IMPERFECTIONS: Details &
Key
Read or relate the following details to the class while showing
the check-table on the overhead projector.
Codes shown at end of each item below is the expected category
to be checked on table.

1. Our spinal column, clearly homologous to the "suspension
bridge" support structure in tetrapods, must serve as a
vertical load-bearing column in people, bringing an abundance
of classic back problems when its support is compromised. (CO)

2. Our larynx: Occupies a lower level than it does
in other animals (creating a larger space in our throat and pharynx
for tongue movements and other changes for generating complex
subtle sounds (speech), but creates a liability in that our food
path crosses the air path, making us more likely to choke compared
to other animals, since food can become
more easily caught in our air path. (CO)

3. Our Eustachian tube (ear canal), homologous to a
gill cleft in fishes, serves to equalize air pressure on opposite
sides of our eardrum. Small changes in air pressure (due to altitude
change, or other cause), can bring severe ear pain, especially
if the tube is swollen closed due to a cold, and is often subject
to infection. (CO)

5. Our "wisdom teeth" (3rd molars), sometimes
never develop, often become impacted, may require surgical removal.
Is this "wise design", or the unfortunate result of
reduced facial projection as the teeth
reduced in size over the course of human evolution? (VE)

6. Our ear-wagging muscles. (VE)

7. Sickle Cell Anemia: caused by a molecular mechanism
which, in a moderate (heterozygous) dose, protects against malaria,
but in its full dose (homozygous recessive), produces disabling
disease of sickle cell anemia. (CO)

8. The flippers of seals and sea lions are clearly
homologous to the legs of tetrapods, and work quite well in the
water, but make for very clumsy locomotion on land. (CO)

9. Tree kangaroos show limited adaptations of their
limbs to their arboreal existence, but they're still relatively
clumsy in the trees, and they are also not as fit for activity
on the ground as their ground-dwelling relatives. (CO)

10. Anteaters develop teeth during fetal development
and then lose them before birth. (VE)

11. Terrestrial salamanders develop gills and fins
but only during fetal development. (VE)